Sulfonation-Induced Cross-Linking and Nanostructural Evolution of a Thermoplastic Elastomer for Ordered Mesoporous Carbon Synthesis: A Mechanistic Study

Authors

Mark Robertson, University of Southern MississippiFollow
Andrew Barbour, University of Southern Mississippi
Anthony Griffin, University of Southern Mississippi
Alejandro Guillen Obando, University of Southern Mississippi
Paul Smith, University of Southern Mississippi
Zhe Qiang, University of Southern MississippiFollow

Document Type

Article

Publication Date

9-20-2023

School

Polymer Science and Engineering

Abstract

Direct pyrolysis of self-assembled block copolymers (BCPs) is a resource-efficient method for synthesizing ordered mesoporous carbons (OMCs), through which the resulting pore textures and properties are often collectively determined by the precursor identity and processing pathways. Previous works in this area heavily rely on the use of polyacrylonitrile-based BCP systems, which employ a high-temperature cross-linking reaction that can impact the degree of ordering in their nanostructures. Recently, thermoplastic elastomers have been employed as an emerging OMC precursor, demonstrated by commodity grade polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS). This method requires solid-state, sulfonation-induced cross-linking, involving simultaneous reactions with both the majority poly(ethylene-ran-butylene) phase and the polystyrene segments. This work elucidates the fundamentals of how the reaction mechanism and condition govern SEBS nanostructure development, which deconvolutes distinct contributions from sulfonation and cross-linking. Specifically, small-angle X-ray scattering results, in conjunction with chemical evolution investigations, indicate that polystyrene sulfonation is primarily responsible for increased domain spacing that is mediated through competition between thermodynamically driven nanostructure rearrangement and kinetic trapping from cross-linking. The conversion of cross-linked SEBS, obtained from varying reaction conditions, to OMCs is also studied for establishing critical process–structure relationship. These fundamental understandings provide key insights about rational system design of SEBS-derived OMCs, prepared through two steps of sulfonation-induced cross-linking and direct pyrolysis.

Publication Title

ACS Applied Engineering Materials

Volume

1

Issue

10

First Page

2577

Last Page

2588

Recommended Citation

Robertson, M., Barbour, A., Griffin, A., Obando, A. G., Smith, P., Qiang, Z. (2023). Sulfonation-Induced Cross-Linking and Nanostructural Evolution of a Thermoplastic Elastomer for Ordered Mesoporous Carbon Synthesis: A Mechanistic Study. ACS Applied Engineering Materials, 1(10), 2577-2588.
Available at: https://aquila.usm.edu/fac_pubs/21706